Flush valves are well known in the art. Although many different types of flush valves are known, two types of flush valves that are commonly used rely upon an auxiliary valve to relieve a pressure chamber to allow the main valve to open for a flush. For example, see U.S. Pat. Nos. 5,881,993, 6,913,239 and 7,980,528 incorporated herein by reference. In order to initiate a flush cycle, that is, to flush the fixture, the auxiliary valve must be unseated. Typically this is accomplished by the use of a gland that extends from an auxiliary valve member. Engaging the gland, such as by striking the side of the gland, will tilt the auxiliary valve member off of the valve seat. As the flush cycle proceeds, the auxiliary valve member reseats allowing the pressure chamber to repressurize causing the main valve to close. Although typical flush valves have been designed to provide a single flush volume, dual mode flush valves have become increasingly important as a way to conserve water. Dual mode flush valves provide the user the ability to select between a higher volume flush and a lower volume flush.
In general, two types of actuation mechanisms are known in the art: manual and automatic. Manual actuation is accomplished through a user initiated process, traditionally by interaction with a mechanical handle. Automatic actuation is accomplished through the use of sensors to determine when a user is present and to actuate the flush valve without the need for direct user initiation, for example when the user has completed usage of the fixture.
There is a need to combine the water conservation of a dual mode flush valve with the reliability of a manual actuation and the ease of use and hygiene of automatic actuation.